[InstCombine] matchFunnelShift - support non-uniform constant vector shift amounts (PR46895)

Complete basic PR46895 fixes by refactoring D87452/D88402 to allow us to match non-uniform constant values.

We still don't handle non-uniform vectors that contain undef elements, but that can wait until we have a decent generic mechanism for this.

Differential Revision: https://reviews.llvm.org/D88420
This commit is contained in:
Simon Pilgrim 2020-10-08 12:56:27 +01:00
parent a4e27220c2
commit 5415fef3ab
3 changed files with 22 additions and 19 deletions

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@ -2079,11 +2079,20 @@ static Instruction *matchFunnelShift(Instruction &Or) {
// matches a subtraction on the R operand.
auto matchShiftAmount = [&](Value *L, Value *R, unsigned Width) -> Value * {
// Check for constant shift amounts that sum to the bitwidth.
// TODO: Support non-uniform shift amounts.
const APInt *LC, *RC;
if (match(L, m_APIntAllowUndef(LC)) && match(R, m_APIntAllowUndef(RC)))
if (LC->ult(Width) && RC->ult(Width) && (*LC + *RC) == Width)
return ConstantInt::get(L->getType(), *LC);
const APInt *LI, *RI;
if (match(L, m_APIntAllowUndef(LI)) && match(R, m_APIntAllowUndef(RI)))
if (LI->ult(Width) && RI->ult(Width) && (*LI + *RI) == Width)
return ConstantInt::get(L->getType(), *LI);
// TODO: Support undefs in non-uniform shift amounts.
Constant *LC, *RC;
if (match(L, m_Constant(LC)) && !LC->containsUndefElement() &&
match(R, m_Constant(RC)) && !RC->containsUndefElement() &&
match(L, m_SpecificInt_ICMP(ICmpInst::ICMP_ULT, APInt(Width, Width))) &&
match(R, m_SpecificInt_ICMP(ICmpInst::ICMP_ULT, APInt(Width, Width)))) {
if (match(ConstantExpr::getAdd(LC, RC), m_SpecificInt(Width)))
return L;
}
// For non-constant cases, the following patterns currently only work for
// rotation patterns.

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@ -100,13 +100,12 @@ define <2 x i17> @fshr_v2i17_constant_splat_undef1(<2 x i17> %x, <2 x i17> %y) {
ret <2 x i17> %r
}
; TODO: Allow arbitrary shift constants.
; Allow arbitrary shift constants.
; TODO: Support undef elements.
define <2 x i32> @fshr_v2i32_constant_nonsplat(<2 x i32> %x, <2 x i32> %y) {
; CHECK-LABEL: @fshr_v2i32_constant_nonsplat(
; CHECK-NEXT: [[SHR:%.*]] = lshr <2 x i32> [[X:%.*]], <i32 17, i32 19>
; CHECK-NEXT: [[SHL:%.*]] = shl <2 x i32> [[Y:%.*]], <i32 15, i32 13>
; CHECK-NEXT: [[R:%.*]] = or <2 x i32> [[SHL]], [[SHR]]
; CHECK-NEXT: [[R:%.*]] = call <2 x i32> @llvm.fshl.v2i32(<2 x i32> [[Y:%.*]], <2 x i32> [[X:%.*]], <2 x i32> <i32 15, i32 13>)
; CHECK-NEXT: ret <2 x i32> [[R]]
;
%shr = lshr <2 x i32> %x, <i32 17, i32 19>
@ -143,9 +142,7 @@ define <2 x i32> @fshr_v2i32_constant_nonsplat_undef1(<2 x i32> %x, <2 x i32> %y
define <2 x i36> @fshl_v2i36_constant_nonsplat(<2 x i36> %x, <2 x i36> %y) {
; CHECK-LABEL: @fshl_v2i36_constant_nonsplat(
; CHECK-NEXT: [[SHL:%.*]] = shl <2 x i36> [[X:%.*]], <i36 21, i36 11>
; CHECK-NEXT: [[SHR:%.*]] = lshr <2 x i36> [[Y:%.*]], <i36 15, i36 25>
; CHECK-NEXT: [[R:%.*]] = or <2 x i36> [[SHL]], [[SHR]]
; CHECK-NEXT: [[R:%.*]] = call <2 x i36> @llvm.fshl.v2i36(<2 x i36> [[X:%.*]], <2 x i36> [[Y:%.*]], <2 x i36> <i36 21, i36 11>)
; CHECK-NEXT: ret <2 x i36> [[R]]
;
%shl = shl <2 x i36> %x, <i36 21, i36 11>

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@ -122,13 +122,12 @@ define <2 x i17> @rotr_v2i17_constant_splat_undef1(<2 x i17> %x) {
ret <2 x i17> %r
}
; TODO: Allow arbitrary shift constants.
; Allow arbitrary shift constants.
; TODO: Support undef elements.
define <2 x i32> @rotr_v2i32_constant_nonsplat(<2 x i32> %x) {
; CHECK-LABEL: @rotr_v2i32_constant_nonsplat(
; CHECK-NEXT: [[SHL:%.*]] = shl <2 x i32> [[X:%.*]], <i32 17, i32 19>
; CHECK-NEXT: [[SHR:%.*]] = lshr <2 x i32> [[X]], <i32 15, i32 13>
; CHECK-NEXT: [[R:%.*]] = or <2 x i32> [[SHL]], [[SHR]]
; CHECK-NEXT: [[R:%.*]] = call <2 x i32> @llvm.fshl.v2i32(<2 x i32> [[X:%.*]], <2 x i32> [[X]], <2 x i32> <i32 17, i32 19>)
; CHECK-NEXT: ret <2 x i32> [[R]]
;
%shl = shl <2 x i32> %x, <i32 17, i32 19>
@ -165,9 +164,7 @@ define <2 x i32> @rotr_v2i32_constant_nonsplat_undef1(<2 x i32> %x) {
define <2 x i36> @rotl_v2i36_constant_nonsplat(<2 x i36> %x) {
; CHECK-LABEL: @rotl_v2i36_constant_nonsplat(
; CHECK-NEXT: [[SHL:%.*]] = shl <2 x i36> [[X:%.*]], <i36 21, i36 11>
; CHECK-NEXT: [[SHR:%.*]] = lshr <2 x i36> [[X]], <i36 15, i36 25>
; CHECK-NEXT: [[R:%.*]] = or <2 x i36> [[SHL]], [[SHR]]
; CHECK-NEXT: [[R:%.*]] = call <2 x i36> @llvm.fshl.v2i36(<2 x i36> [[X:%.*]], <2 x i36> [[X]], <2 x i36> <i36 21, i36 11>)
; CHECK-NEXT: ret <2 x i36> [[R]]
;
%shl = shl <2 x i36> %x, <i36 21, i36 11>